Something to watch with pretreated patches.. they are often times far too wet, which might be making your attempt at drying the bore not complete. Also a lot of times they solution they use has lots of water in it. While water works real well for swabbing, anyone that spit patches tell you, a little spit goes a long way. Water is the hardest of all solutions to remove from the barrel.

Next time you go to the range, get some Windex or makes some car windshield washer solution & isopropyl alcohol 50/50 solution. Spritz the patch lightly and swab with that in short strokes down the barrel. Then flip that and do it all over again. After that a couple dry patches, then load.

Also, try some 250 grain shockwaves and kick your pyrodex load after a couple shots with 100 grains to 120 grains of loose powder. And see what kind of groups that rifle will shoot with that.

You have a great rifle. And a good first range session. It looks like a little work and you will have a great rifle there.